Mobile devices are often configured to exchange data wirelessly with other nearby media devices. For example, a cellphone may be wirelessly connected to an earpiece or a laptop computer may be wirelessly connected to a printer. Additionally, a cellphone or tablet may be wirelessly connected to a loudspeaker for streaming music. For example, the OnBeat Xtreme™ loudspeaker docking station by JBL is an example of such a loudspeaker that may be wirelessly connected to a mobile device. Communication between wireless devices within an indoor network may be coordinated, especially when the network includes more than one of the same type of device (e.g., two or more wireless loudspeakers). Such coordination would be assisted by an accurate determination of the location of the mobile device relative to the media devices.
There are a number of different existing methods for determining the location of a mobile device using wireless signals. For example, many mobile devices (e.g., cellphones, tablet computers) are configured to use global positioning technology (GPS) for determining their location. However, GPS technology does not work well indoors without additional infrastructure, such as ground relay stations.
Other locating methods that are based on the concepts of triangulation or trilateration are also known. However, such methods often require communication between more than two devices, and/or fixed spacing between the devices.
Wireless devices are often configured to exchange data with other nearby wireless devices using Bluetooth or WiFi technology. Bluetooth, which is standardized as IEEE 802.15.1, is a wireless technology standard for exchanging data over short distances (using short-wavelength radio transmissions in the ISM band from 2400-2480 MHz) from fixed and mobile devices, creating personal area networks (PANs) with high levels of security. Bluetooth includes a number of signal parameters that relate to signal strength, including: Received Signal Strength Indicator (RSSI), Link Quality, Received Power Level, and Transmit Power Level (TPL). Hossain et al, disclose a study of using such signals for determining the location of a wireless device, “A Comprehensive Study of Bluetooth Signal Parameters for Localization”, IEEE, 2007.